Human cytomegalovirus (HCMV) is the most common viral infection known to be transmitted in utero. Congenital infection with HCMV is the leading cause of deafness and can result in death or major neurodevelopmental defects including chorioretinitis and mental retardation. The disease burden due to HCMV currently exceeds that occurring during the height of the epidemic rubella era. HCMV also produces life threatening sequelae in persons who are immunocompromised by drug therapy for transplantation, cancer treatment, or who have HIV infection. Aviron proposes to develop a live attenuated vaccine for the prevention of disease caused by HCMV. They successfully developed molecular genetic processes to engineer HCMV. Using a Phase I SBIR grant, they generated a well-defined series of five recombinant HCMV vaccine candidates. Each candidate contains genetically stable portions of the nonattenuated Toledo HCMV viral genome within a background of the safe, overattenuated Towne HCMV genome. In Phase II of the SBIR program, they propose to produce two of the five chimeras for human testing and determine their safety and immunogenicity in a Phase I clinical trial in collaboration with the NIH VTEU network. Their goal is to select a vaccine strain based on the human data for final commercial development. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE